John A. Brabyn

Seeing into old age : Vision function beyond acuity

PURPOSE To provide a comprehensive description of vision function beyond acuity in older individuals. METHODS A sample of 900 individuals between the ages of 58 and 102 years (mean age of 75.5) was binocularly tested wearing habitual correction on a battery of psychophysical tests including high and low contrast acuity, low contrast low luminance acuity, disability glare, contrast sensitivity, color vision, stereoacuity, recovery from glare, and attentional visual fields. RESULTS High contrast acuity is reasonably well maintained on average, even into very old ages. Spatial vision measures under conditions of reduced contrast or luminance, or glare reveal significant impairment in a large portion of the aged. Many older individuals also have greatly reduced stereopsis, poor color discrimination, and severely restricted peripheral fields under conditions of divided attention. A single exponential function relating performance to age fits all spatial vision data sets. The function for individual spatial measures lies at different positions along the age scale. The derived aging function with a time constant of approximately 15 years also fits results from other recent aging studies of acuity and contrast sensitivity. CONCLUSIONS Standard visual acuity underestimates the degree of vision function loss suffered by many older individuals under the nonoptimal viewing conditions encountered in daily life. All spatial vision functions show a similar rate of decline with age of the population, but the age at which decline begins varies among measures.

Is Vision Function Related to Physical Functional Ability in Older Adults

OBJECTIVES To assess the relationship between a broad range of vision functions and measures of physical performance in older adults. DESIGN Cross-sectional study. SETTING Population-based cohort of community-dwelling older adults, subset of an on-going longitudinal study. PARTICIPANTS Seven hundred eighty-two adults aged 55 and older (65% of living eligible subjects) had subjective health measures and objective physical performance evaluated in 1989/91 and again in 1993/95 and a battery of vision functions tested in 1993/95. MEASUREMENTS Comprehensive battery of vision tests (visual acuity, contrast sensitivity, effects of illumination level, contrast and glare on acuity, visual fields with and without attentional load, color vision, temporal sensitivity, and the impact of dimming light on walking ability) and physical function measures (self-reported mobility limitations and observed measures of walking, rising from a chair and tandem balance). RESULTS The failure rate for all vision functions and physical performance measures increased exponentially with age. Standard high-contrast visual acuity and standard visual fields showed the lowest failure rates. Nonstandard vision tests showed much higher failure rates. Poor performance on many individual vision functions was significantly associated with particular individual measures of physical performance. Using constructed combination vision variables, significant associations were found between spatial vision, field integrity, binocularity and/or adaptation, and each of the functional outcomes. CONCLUSIONS Vision functions other than standard visual acuity may affect day-to-day functioning of older adults. Additional studies of these other aspects of vision and how they can be treated or rehabilitated are needed to determine whether these aspects play a role in strategies for reducing disability in older adults.

Vision and Driving Self-Restriction in Older Adults

Objectives: To assess driving self‐restriction (vision related and nonvision related) in relation to vision test performance of older adults.

The Smith-Kettlewell Institute (SKI) longitudinal study of vision function and its impact among the elderly : An overview

We present an overview of a multifaceted longitudinal study of vision function and its interaction with daily activities, health, and well-being among 900 persons aged 58 to 102 years at the first visit. Standard vision measures as well as nonconventional tests designed to assess visual performance under the nonideal conditions encountered in everyday life were used. Here we summarize a few of the findings to date, with an emphasis on a direct comparison of declines in different aspects of vision function with age. The rates of declines with advancing age vary widely for the different vision functions. Also described is the reading performance of the sample and its association with some of the vision measures. Furthermore, we describe some of the associations between vision test scores and extensive longitudinal health and functioning data collected by the Buck Center for Research in Aging. Findings show that many older people with good acuity are effectively visually impaired in performing everyday tasks involving low and changing light levels, stereopsis, glare, and low contrast. We also found that vision under nonideal conditions cannot be predicted from standard acuity on an individual basis.

Night driving self-restriction : Vision function and gender differences

Purpose. The purpose of this study was to evaluate gender differences in the relationship between night driving self-restriction and vision function in an older population. Methods. Night driving self-restriction patterns (assessed by questionnaire) were examined cross-sectionally in relation to age, gender, health and cognitive status, depression, and vision function in a sample of 900 elders (mean age, 76 years) living in Marin County, California. Results. Of the total sample, 91% of men and 77% of women were current drivers. The mean age of the drivers was 73.3 years (range, 58–96 years). Among current drivers, women had slightly better vision function than men on most measures (low-contrast acuity, contrast sensitivity, low-contrast acuity in glare, low-contrast, low-luminance acuity, and glare recovery) but were twice as likely as men to restrict their driving to daytime. Men showed significant associations with avoidance of night driving on four spatial vision measures (high- and low-contrast acuity, low-contrast, low-luminance acuity, and contrast sensitivity). For women, in addition to these measures, a significant association was seen for low-contrast acuity in glare. Neither men nor women showed significant associations between driving restriction and performance on the other vision measures examined (glare recovery time, attentional field integrity, or stereopsis). The vision measures most predictive of self-restriction were contrast sensitivity for men and low-contrast acuity in glare for women. Conclusions. Including both cessation and self-restriction, men over age 85 years are 6.6 times more likely than women to be driving at night. For both genders, vision plays a significant role in the self-restriction decision. A higher percentage of men than women continue to drive at night with poor vision. Men’s night-driving cessation was associated with contrast sensitivity and depression, whereas women’s night-driving cessation was associated with low-contrast acuity in glare as well as age.

Reading performance in older adults with good acuity.

Purpose. This study evaluated factors affecting reading performance in a sample (N = 544) of older adults (mean age 72.8 years, range 58 to 102) with good high-contrast acuity (≥20/32). Methods. Using the Pepper Reading Test, the relationship between reading rate and several vision measures was assessed. Results. Mean corrected reading rate fell substantially over the age range tested despite the fact that these individuals all had good acuity. However, multiple regression analysis indicated that when other measures were taken into account (most notably, low-contrast vision, motor ability, and attentional field integrity), age was not a significant independent predictor of corrected reading rate. Conclusion. Reading is an important skill, and ways of enhancing reading performance should be explored. Good high-contrast acuity does not assure that older individuals can read satisfactorily.

Face recognition in the elderly.

Purpose. The purpose of this study was to assess face recognition ability in a large sample of elders (n = 572, mean age = 78.1 years) and to identify factors that affect performance. Methods. Face recognition was measured by presenting standardized faces of varying sizes to simulate normal-sized faces at different viewing distances. Subjects were asked to identify the name of the person and their facial expression. Threshold equivalent viewing distance (EVD) was calculated. High- and low-contrast acuity, contrast sensitivity, low-contrast/low-luminance acuity, disability glare, stereoacuity, and visual field measures (with and without an attentional task) were also measured. These vision measures, along with demographic information (age, sex, education) and cognitive status, were included in a multiple regression analysis to determine which factors predicted task performance. Results. This cross-sectional sample of elders showed significant declines in face recognition with age. Mean threshold EVD ranged from 8.0 m for participants ≤70 years of age to 2.2 meters for those over 85 years. Multiple regression analysis revealed that age, sex, years of education, spatial vision, and cognitive status were all significant predictors of face recognition, accounting for approximately 46% of the variability. Spatial vision (high-contrast acuity) and age were the best predictors. Although each spatial vision measure was significantly correlated with face recognition, adding low-contrast or contrast sensitivity measures to the regression analysis explained no more variance than age and high-contrast acuity alone. Conclusions. The marked decline in face recognition ability in elders is related to declines in spatial vision and cognitive status. All spatial vision measures have similar predictive ability for face recognition.

The Relation Between Visual Acuity and Other Spatial Vision Measures

Purpose To examine to what extent measurement of standard visual acuity allows prediction of other spatial vision measures on an individual basis when high correlations exist between visual acuity and the other measures. Methods A series of spatial vision functions were measured in a sample of 900 community-dwelling older observers. Regression analysis was performed, and correlation coefficients were calculated between standard high-contrast visual acuity and other spatial vision measures including contrast sensitivity, low-contrast acuity, low-contrast low-luminance acuity (SKILL card), and disability glare acuity. Results All measures were highly and significantly correlated with standard visual acuity (r = 0.68 to 0.91). Despite the high correlations, many predictions of the other spatial vision measures from the correlation with standard acuity fell considerably outside of acceptable ranges determined by repeatability. The influence of the range of values in correlations is emphasized. Conclusions Other spatial vision measures cannot be predicted on an individual basis from visual acuity despite high and significant correlations between the measures.

New orientation and accessibility option for persons with visual impairment: transportation applications for remote infrared audible signage

Background:For a blind or visually impaired person, a vital prerequisite to accessing any feature of the built environment is being able to find this feature. Braille signs, even where available, do not replace the functions of print signage because they cannot be read from a distance. Remotely readable infrared signs utilise spoken infrared message transmissions to label key environmental features, so that a blind person with a suitable receiver can locate and identify them from a distance.

A Review of Mobility Aids and Means of Assessment

Mobility has been defined by Foulke (22) as “the ability to travel safely, comfortably, gracefully, and independently through the environment.” The most popular mobility aid is, of, course, the long cane, but whether or not this solves the problems of “grace”and “independence”is questionable at best. The long cane, introduced in its present form by Hoover (27) in the late 1940s, effectively allows detection of obstacles within a 3-foot range, and tends to warn other pedestrians to get out of the way. The former feature requires fast stopping reaction when an obstacle is encountered, while the latter does not add to the grace and independence of travel.